Automatic magnetic brake for band saws



Dec. 8, 1953 J. P. MORGAN AUTOMATIC MAGNETIC BRAKE FOR BAND SAWS FiledAug. 2, 1950 Joseph R Morgan BY Q4, WW

I N V EN TOR.

' Atlomrjs Patented Dec. 8, 1953 AUTOMATIC MAGNETIC BRAKE For: BAND sAwsJoseph P. Morgan, Wampum,

Pa.,' assignor of forty-nine per cent to Harry CriscLNew Castle, Pa.

Application August 2, 1950, Serial N 0. 177,203

2 Claims.

The present invention relates to new and useful improvements in safetymeans for band saws and more particularly to an improved automaticallyoperated emergency safety mechanism to halt further travel of the bandsaw should the same become broken.

More specifically the invention comprises a normally de-energizedelectro magnet controlled by an electric switch which is actuated whenthe same saw breaks to energize the magnet and to which the broken bladeof the saw is attracted for holding the saw from further movement untilthe power for operating the saw machine is cut off. An important objectof the invention is to provide automatic switch means for the electromagnet which is held in open position by an unbroken band saw andproviding spring means for closing the switch when the saw blade breaks.

A further object is to provide a device of this character of simple andpractical construction, which is efiicient and reliable in operation,relatively inexpensive to manufacture and install in operative positionon the saw machine and which is otherwise well adapted for the purposesfor which the same is intended.

Other objects and advantages reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming part hereof, wherein likenumerals refer to like parts throughout, and in which:

Figure 1 is a fragmentary side elevational view of a saw machine withparts broken away and shown in section to show the electro magnet andswitch mounted in position thereon;

Figure 2 is an enlarged sectional view of the switch taken on a line2--2 of Figure l; and

Figure 3 is an enlarged front elevational view of the magnet.

Referring now to the drawing in detail wherein for the purpose ofillustration I have disclosed a preferred embodiment of the invention,the numeral 5 designates the guard or housing of a conventional type ofband saw machine provided with the usual vertically travelling endlesssaw blade 6 which passes through the table I.

A switch housing 8 is secured to the underside of the table behind thefront flight 9 of the saw blade, the housing enclosing a switchdesignated generally at I!) and which includes a pair of stationarycontacts I I and I2 suitably insulated from the switch housing and asliding switch arm I3 positioned between the stationary contacts withone end of the arm projecting outwardly of the housing and formed with ayoke I4 in which a roller I5 is journalled. A coil spring I6 ispositioned in the switch housing at the rear end of switch arm l3 andengages a flange or cross pin I 1 fixed to the arm I3 to urge the latteroutwardly.

A movable contact designated generally at I8 is suitably secured to theswitch arm I3 and includes a pair of oppositely extending arms I9 and 20positioned for engaging the contacts II and I2 upon an outward movementof the switch arm [3 by spring I6. The movable contact I8 is preferablyadjustable on the switch arm it for adjusting the contact arms I9 and 20relative to the contacts II and I2.

An electric circuit 2| connects the contacts II and i2 with a suitablesource of current (not shown) and with an electromagnet 22 of aconventional type secured to the rear of the guard 5 in a positionspaced from the rear flight 23 of the saw blade 6. In the operation ofthe device the spring I6 urges sliding switch arm l3 outwardly of theswitch housing 8 to hold the roller I5 against the front flight 9 of thesaw blade 6, the 25 spring being held under tension by the saw blade andthe saw blade limiting outward movement of the switch arm I3 to hold themovable contact arms I9 and 20 spaced from the stationary contacts I Iand I2, as shown in Figure 2 of the drawmgs.

The breakage of the saw blade usually occurs adjacent the table I andimmediately upon such breakage spring I6 will slide switch arm I3forwardly to close the circuit by bridging the stationary contacts I Iand I2 by the contact arms I9 and 20 to thus energize the magnet 22which thus attracts the rear flight 23 of the saw blade to hold thelatter and halt its further. movement until the operator cuts off themachine and replaces the saw.

In view of the foregoing description taken in conjunction with theaccompanying drawings it is believed that a clear understanding of thedevice will be quite apparent to those skilled in this art. A moredetailed description is accordingly deemed unnecessary.

It is to be understood, however, that even though there is herein shownand described a preferred embodiment of the invention the same issusceptible to certain changes fully comprehended by the spirit of theinvention as herein described and the scope of the appended claims.

Having described the invention, what claimed as new is:

1. In combination with a band saw, a switch including a slidable switcharm, spring means tending to close the switch, said arm being held inopen position against and by the saw and against the urging of thespring and closed by the spring upon a break in the saw, and anelectrically energized magnet connected to and controlled by the switch,said magnet being positioned adjacent the saw to attract and hold thelatter stationary by the closing of the switch.

2. In combination with a band saw, a switch including a slidable switcharm, a roller at one end of the arm bearing against a travelling saw,spring means projecting the arm and holding the roller against the saw,a contact carried by the arm, a stationary contact in the path ofmovement of the first named contact and held spaced 4 therefrom by thesaw, and an electro-magnet supported adjacent the saw and connected in acircuit with said contacts to energize the magnet and to attract andhold the saw stationary upon a break in the saw to release the switcharm and close the contacts.

JOSEPH P. MORGAN.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,927,203 De Groote Sept. 19, 1933 2,286,589 Tannewitz June16, 1942 2,395,905 Oet'zel Mar. 5, 1946

